A device of this type is known from DE 196 52 801 C1. The energy source in this invention supplies the piezoelectric actuator with a specified amount of energy for which the value is derived from a temperature-dependent key field.
The speed and stability of piezoelectrically controlled injection valves for internal combustion engines, both for petrol and also for diesel applications, has made them ever more attractive to auto makers. However the reproducibility of the amount of fuel injected depends directly on the precision of the movements of the valve needle. Since the needle is driven directly by a piezoelectric actuator via a movement converter or a servo valve in the diesel area it is necessary to control this actuator across the entire temperature range electrically with the appropriate precision.
DE 196 52 801 C1 proposes supplying the piezoelectric actuators with constant energy, with the value of the energy to be actually fed being obtained from the measured temperature from a key field and the charge voltage being subject to regulation to arrive at the desired amount of energy.
Controlling a typical piezoelectrically operated injection valve with constant energy however means that it looses around a 15% extension in the temperature range from 0° C. to 125° C. in accordance with FIG. 2. It would now be possible to regulate the energy here too through a corresponding key field to a larger amount of energy at higher temperatures, to compensate for the loss of extension. This is however only possible if in the final stage there is sufficiently large computing power available and when the energy feed to the actuator can be measured within the device.